This invention relates to devices for temporarily plugging installed sewer lines as must be done on occasions when repair work or pressure testing is required.
There are devices presently available which are used for the same purpose as this invention, namely, to stop the normal flow of water in a pipe line. Such plugs or stoppers are required in a line, for example, when repairs or maintenance work must be done or when leaks occur which must first of all be located and then be measured to determine if it is necessary to excavate and replace a section of the buried line. The known devices of this type are quite complex and bulky which makes them difficult to assemble and then install in the end of a pipe which is accessible in most cases only through a manhole of limited size. Since sewer line plugs are expected to provide a fluidtight seal even when the pressure exerted by the head of water in the pipe is fairly high, it is important that the plug be capable of effecting a proper seal even when the interior of the line is dirty or has otherwise deteriorated and this has not always been the case when conventional plugs or stoppers are used.